Accelerating Fe^III-Aqua Complex Reduction in an Efficient Solid-Liquid-Interfacial Fenton Reaction over the Mn-CNH...

The sluggish regeneration rate of Fe^II and low operating pH still restrict the wider application of classical Fenton process (Fe^II/H₂O₂) for practical water treatment. To overcome these challenges, we exploit the Mn-CNH co-catalyst to construct a solid-liquid interfacial Fenton reaction and accelerate the Fe^III/Fe^II redox cycle at the interface for sustainably generating ^•OH from H₂O₂ activation. The Mn-CNH co-catalyst exhibits an excellent regeneration rate of Fe^II (∼65%) and a high tetracycline removal rate (K_obs) of 0.0541 min^-1, which is 19.0 times higher than that of the Fe^II/H₂O₂ system (0.0027 min^-1) at a near-neutral pH (pH ≈ 5.8), and it also attains 100% degradation of sulfamethoxazole, rhodamine B, and methyl orange. The cyclic mechanism of Fe^III/Fe^II is further elucidated in an atomic scale by combining characterizations and density functional theory calculations, including Fe_aq^III specific adsorption and the electron-transfer process. Mn active sites can accumulate electrons from the matrix and adsorb Fe_aq^III to form Mn-Fe bonds at the solid-liquid interface, which accelerate electron transfer from Mn-CNH to Fe_aq^III and promote the regeneration of Fe^II at a wide pH range with a lower energy barrier. The regeneration rate of Fe^II in the Mn-CNH/Fe^II/H₂O₂ system outperforms the benchmark Fenton system and other typical metal nanomaterials, which has great potential to be widely applied in actual environment remediation.